This invention relates to seals for use between oil field casing and wellheads, and more particularly to elastomeric seals for such use under conditions of high temperature and pressure.
During the course of drilling wells for the production of crude oil, natural gas, water, steam and other fluids it is not uncommon to encounter pressures and temperatures of a wide range, and also chemicals that are corrosive and/or otherwise harmful to the drilling equipment. Past efforts to combat these problems have included wellhead seals of many configurations and compositions that have produced results of varying success or failure. The problem is more difficult when attempting to adequately seal between a wellhead and a non-machined or otherwise rough casing surface, especially when extremes of pressure, temperature and/or chemical activity are present. Oilfield casing diameters are manufactured with a tolerance range of plus 1 percent to minus one-half of one percent of the nominal outside diameter, and this range can be so large that the traditional elastomer seals cannot bridge the gap between the wellhead and casing. Thus prior to the present invention there was a need for a new seal that would maintain its sealing effect throughout the entire range of tolerance variation, as well as over a wide temperature and pressure range.